The present invention relates to an internal combustion engine with at least one main combustion chamber and an ignition chamber connected therewith.
Internal combustion engines of this general type are known in the art, for example from the German patent application No. P 3,025,926.8. The internal combustion engine disclosed in this reference has a center electrode which extends from its free end forming a spark gap into the ignition chamber. Heat of the center electrode must be withdrawn so as to prevent the center electrode from attaining unacceptably high temperatures which can result in uncontrolled or surface ignition. The withdrawal of heat is performed with the aid of an insulator shoe which is formed on the insulator and surrounds the center electrode at least over a half of its longitudinal portion extending into the ignition chamber. The insulator shoe transfers the heat quantities which are received from the center electrode and can lead to the unacceptably high temperatures, to the insulator. Since the insulator shoe is also exposed to hot combustion gases, it has a great cross-section in the region directly adjacent to the insulator. It is thereby provided at the part of the ignition chamber which extends arround the center electrode, has a greater diameter than the part of the ignition chamber which extends between the main combustion chamber and the spark gap. Thereby, a chamber is available behind the spark gap for receiving residual gases of a predetermined combustion. By the time of ignition, sufficiently combustible mixture is located in the spark gap. It is desirable to increase the gas-receiving possibilities of this part of the ignition chamber, which extends around the center electrode. However, often the diameter of the chamber for the provision of the ignition chamber so that the inner cross-section of the ignition chamber is limited so that the inner cross-elongation of the ignition chamber has the disadvantage that for avoiding an unacceptable temperature increase on the center electrode and the insulation shoe, at least the latter must have a great cross-section. The great cross-section of the insulating shoe so narrows the inner cross-section of the ignition chamber that the intended increase of the ignition chamber can be attained only partially or not attained at all.